IURTP Lilly-Dickey Woods Enters a Global Forest Matrix

Written by Maggie Messerschmidt
Graduate Student at IU School of Public and Environmental Affairs
March 12, 2013

“That part of Brown County is amazing for its roadlessness and forest cover,” says Dan Johnson, IU researcher and Biology PhD candidate, referring to Lilly-Dickey Woods and surrounding forest cover. “You can literally see it from space,” he says, pointing to a distinct dark green patch on a Google Earth aerial image from his office computer, reflecting its distinguished status as one of the densest forest communities in the lower Midwest and a forest of native hardwood trees to boot. While most of Brown County’s forests were cleared in the late 1800s, Lilly-Dickey Woods escaped such a fate. The woods have not been cleared in at least 150 years–in fact, there may be sections that were never cleared–and were gifted to Indiana University in 1942 for botanical research and art studies. The property is located to the north of Nashville, Indiana, off of Bear Wallow Hill Road and borders The Nature Conservancy’s 350-acre Hitz-Rhodhamel Woods. It is managed by the IU Research & Teaching Preserve. Though it is not available for public recreational use, the forest serves the local community as a carbon sink and as a water catchment and renewal system in its function at the headwaters of the Lower East Fork White River Watershed.

Thanks to its protection and resulting ecological integrity, the 550-acre oak-hickory-maple forest serves as a reference point for other Midwestern forests and as a key site of the forest matrix developed by the Smithsonian Institution Global Earth Observatory. SIGEO is a platform of the Center for Tropical Forest Science (CTFS) that maps and tracks forests around the globe to study forest structure, function, and dynamics–important for the incredible impact of forests on the Earth’s climate. Like other research teams in China, Thailand, Colombia, and Kenya–among other countries–Dan and his team have identified, measured, and mapped 28,000 trees in a plot in the center of Lilly-Dickey Woods that has expanded every year since 2009 until completed in 2012 and now contains 62 acres (25 hectares). Scientists in the SIGEO network are getting at what Dan refers to as the “ground truth,” or the reality of how biomass, or biological material, occurs across a landscape. For the first time, the same methodology will be used to collect forest data on a global scale, that is, for 4.5 million trees at 47 sites and in 21 countries. Analyses performed with the data will take advantage of the uniform methodology, providing an improved level of certainty for conclusions drawn from on-the-ground ecological data. You can’t get that kind of certainty from Google Earth or even from advanced science technology like remote sensing.

Many ecological studies are done without directly comparable data sets. “But now it’s a question of comparing apples to apples,” says Dan. Implications for understanding ecosystems are huge, as scientists will be able to distinguish changes in forest dynamics using similar methodology. The trees mapped in Lilly-Dickey Woods have already been part of an analysis of the global forest matrix to determine whether large trees tend to be grouped together or whether they were more likely to be found farther apart. Such information could later be used to make improved predictions about forest dynamics as we estimate, for example, forest biomass in order to predict the amount of CO2 uptake by forests.

With initial data on tree identification and size completed, I asked Dan what was next. “Let the trees grow,” he says, “and watch what happens.” Dendrometer bands, thin straps of metal around the tree that expand with the tree’s growth, will be checked annually on 1,000 trees while all 28,000 trees will be re-measured every five years. And what will happen to the forest as it undergoes expected drought and climate change? Some climate prediction models suggest that sugar maple will no longer occur south of the Canadian border, due to warming temperatures, though it now dominates the forest understory at Lilly-Dickey Woods. Sugar maples need specific cold conditions to germinate and they are less tolerant of drought. And what will be the impact of the invasive insect pest, Emerald Ash Borer, on Lilly-Dickey’s young and old ash trees? With such pressures on the forest canopy, will community management efforts like those of the Brown County Native Woodlands Project be enough to ward off the threat that invasive species pose for our native forests? The project group of Brown County community members works to impede seed production of Japanese stiltgrass which frequently invades disturbed forest understories. Scientists are especially interested in understanding how such changes in forest structure will affect the forest’s carbon storage capacity over time.

While Brown County’s residents may observe changes in their local woodlands, scientists across the globe will be comparing observations of Lilly-Dickey’s 35 tree species to the dynamics of those 8,500 tree species across the globe to weigh in on a systematic understanding of how forests generally behave. The application of this understanding implies improved bio-monitoring capabilities by the global scientific community, more conscientious planning for the care of ecosystems by public land managers, and improved evaluation and response to the impacts of climate change in communities everywhere.

The project has also been funded by the Center for Tropical Forest Science, the IU Research & Teaching Preserve, the Indiana Academy of Sciences, and the National Science Foundation. The IU Research & Teaching Preserve manages 1,600 acres of protected natural areas for university research, teaching, and outreach.

Stem map of the 25-hectare IU Forest Dynamics Plot at Lilly-Dickey Woods. All stems are color coded by species and the point is scaled by the stem diameter. The red hues are oaks and the green hues are maples. Note the concentration of nearly 3500 pawpaws in the north central area of the plot. There are 35 species total and over 29,000 stems for woody species > 1cm in diameter at breast height. ▼

Forest Dynamics Plot

The Smithsonian Tropical Research Institute (STRI) commissioned Dan Johnson and fellow researchers in Spring 2012 to collect data for a global project aimed at understanding the long-term dynamics of forests.

▲ Dan Johnson measures the DBH (diameter base height) of an ash tree.

The STRI collaboration increased the Lilly-Dickey Woods (LDW) study area from 9 hectares to 25 hectares (about 62 acres) and is now known as the Indiana University Forest Dynamics Plot. Johnson and his crew followed STRI’s strict protocol when they identified, measured, and mapped every tree and shrub within the area. All woody plants will be re-measured every five years to track changes in forest biomass and mortality. IU Biology professors Rich Phillips and Keith Clay will oversee the project into the future. The resulting data will help monitor the health of local forests and their role in the global carbon cycle.

The LDW site became the second Midwestern US forest in the STRI network of forest plots (Smithsonian Institute Global Earth Observatory [SIGEO]). SIGEO, an outgrowth of and companion to the Center for Tropical Forest Research (CTFR), strives to broaden the range of CTFR’s scientific investigations by studying temperate forests, carbon fluxes, and the impacts of climate change on biodiversity and forest function. Data compiled by the SIGEO will allow scientists to better understand and compare the dynamics of multiple types of forests over time. Because every plot follows the same methodology, scientists can directly compare data collected from different forests around the world and detect patterns that would otherwise be impossible to recognize.